In recent years, the popularity of lyophilised drugs has risen and has been accompanied by the development of prefilled syringes, pre-filled dual-chambered syringes and dual chambered cartridges for their administration. This has been driven by the market's need for means to facilitate reconstitution of such drugs, increase dose accuracy, avoid dosing and reconstitution mistakes, and improve patient safety and compliance, particularly in the case of self-administered products.
As no filling, measuring or mixing outside the syringe is required by a user, such syringes are convenient and safe to use and allow rapid administration of drugs, making them ideal for self-administration.
Such prefilled syringes/cartridges typically contain a measured dose of a lyophilised drug, in a first chamber, and a diluent in a second chamber. The two chambers are separated by a movable seal. The diameter of the seal is equal to the internal diameter of the second chamber. On application of pressure to a plunger, the seal is forced longitudinally through the second chamber until it reaches a bulge in the wall of the syringe. The diameter of the seal is less than the diameter of the bulged portion of the syringe such that, when the seal reaches the bulged portion, a channel is formed between the seal and the wall allowing diluent to bypass the seal and enter the first chamber to contact the drug. The drug can then be dissolved in the diluent and administered in the normal manner.
It would be desirable to provide an alternative vessel that can control communication between a first chamber and a second chamber that does not require a bulged wall portion. This is because forming the bulged wall adds complexity to the manufacturing process and may affect the structural integrity of the vessel. It would also be advantageous to be able to convert a regular syringe into a dual-chambered syringe which can control communication between the two chambers. A further problem associated with existing dual chambered syringes is the opportunity for components to become trapped in the bypass portion of the device and/or flow back into the first chamber once mixed. This may require the user to further manipulate the device (e.g. angle) in order to ensure that the components are properly combined and that the full dose is administered, which is inconvenient. It would also be advantageous to be able to convert a regular syringe into a dual-chambered syringe which can control communication between the two chambers.
An alternative approach to a dual-chambered vessel capable of keeping components separate until a desired time are dispenser caps of the type used in the health, cosmetics, nutrition and beverage industries as well as in the sports drinks field. An example of a cap used in the sports drink field is available from Vicap Systems EMEA Ltd, Switzerland. A first component is contained in a specialised bottle cap comprising a closure system. The closure system includes a barrier separating the first component from the contents of a bottle to which the cap is fitted, and a puncture device. The puncture device can be operated to puncture the barrier allowing delivery of the first component into the bottle. Further details can be found at the following URL: www.vicapsystems.eu/products/caps/. Another example of a dispenser cap is a Biphase Cap available from Bormioli Rocco S.p.A., Italy. Further details can be found at the following URL: www.bormioliroccopackaging.com/en/pharma/single-dose/traditional/traditional/biphase-kit.html.
Problems with the dispenser cap approach are that the capacity and dimensions of the caps are restricted by the dimensions of the bottle or vial (particularly the neck) to which the cap is fitted, which are typically a standard size or very market/cost needs oriented. The dispenser cap is also restricted by the way in which standard caps are designed to engage the neck of standard bottles or vials (screw neck, crimp neck). The cap is also limited in terms of providing a stable environment for components because of the chemical structure (material) of the cap, the number of parts used for creating the cap and the sealing process in general, which make it difficult to achieve a hermetically sealed environment.